Document Overview
This is a research article titled "Smart Retrofitting of the Building Stock in Germany in order to Achieve CO2-Neutrality by 2045", published in March 2025 in Current Trends in Civil & Structural Engineering (Volume 11, Issue 4). It was written by Rolf Groß and Lina Schulze Buxloh of FH Aachen University of Applied Sciences, Germany. Its subject is how the building sector can contribute to climate neutrality.
Context and Starting Points
- The article states that the real estate sector was responsible for 35.5% of total energy consumption in Germany in 2022.
- Estimates cited for renovation needs range from 15 to 18 million residential buildings, while the Fraunhofer Institute for Building Physics estimated around 24 million residential buildings need energy-efficient renovation.
- Including non-residential buildings such as daycare centres, schools, hospitals and offices, the article puts the total at about 26 million buildings that do not work efficiently.
- Non-residential buildings make up around 15% of buildings but account for 37% of building-sector energy consumption and about half of building-related greenhouse gas emissions.
Key Findings and Figures
- The actual renovation rate is 1.0% per year, and the article argues that climate targets require raising it to 3.0% per year immediately.
- In 2023, 295,000 apartments and around 30,000 non-residential buildings were newly constructed.
- Buildings are responsible for around 40% of CO2 emissions in the EU.
Political Framework
The article describes EU guidance based on the UN Sustainable Development Goals and the Energy Performance of Buildings Directive (EPBD), whose amendment is to set stricter requirements for existing properties by 2030 through national renovation plans, renovation passports and a uniform energy efficiency scale. It names the Building Energy Act (GEG), the Federal Funding Act for Energy Efficient Buildings (BEG) and the Quality Seal for Sustainable Buildings (QNG) as German instruments, and a planned Digital Building Resource Pass added to the energy certificate.
Role of the Construction Industry
The authors point to lighthouse projects such as "The Ship", "The Edge", "HammerBrooklyn" and the "Cube Berlin" as showing what is technically feasible. They argue that BIM and digital twins are needed for existing buildings, which are largely not affected by these developments, and that laser scanning, AI-supported object recognition and radar-based non-destructive measurement can create digital models of existing stock.
Methodology
The article describes its method only as a "Literature Survey" under Material and Methods. It is a narrative discussion structured around political framework, the task of the economy, and assistance from science, rather than an empirical study.
Role of Science and Skilled Labour
The article notes significant differences in digital affinity among people involved in construction, which it says leads to loss of information across planning, construction and operation. It argues that stakeholders should be involved by considering the added value of each use case and linking data through standards, and that the necessary qualified specialist staff must be available in sufficient numbers.
Why It Matters for Urban Policy
The article concludes that CO2-neutrality by 2045 requires the building stock to be addressed, especially the renovation rate of existing buildings through smart retrofitting, and that political, scientific and economic frameworks must be linked. It is addressed to the political, economic and scientific actors it names.